Report from Amnesty and UN details shocking violence while U.S. slaps sanctions on leaders on each side of the conflict.

Illegal migrants who were abandoned in the desert by human traffickers following their arrival in the northern Sudanese city of Dongola this week. Sudanese officials say traffickers had dumped their victims in the border region’s scorching desert, where 10 died.

Execution, sexual torture, kidnapping, home-burning, ethnic cleansing: atrocities against South Sudan’s suffering civilians are mounting, even as the start of political talks between the warring sides offer a small glimmer of hope.

On Thursday, the UN and Amnesty International published reports detailing horrific violence, and warning of worse to come if the government and rebels fighting for control of the fledgling state are not reined in. The U.S., meanwhile, slapped sanctions on two military leaders, one on each side of the conflict.

“I was three months pregnant, but because I was raped by so many men, the baby came out,” one woman from Unity state told Amnesty. “If I had refused those people, they would have killed me.”

Another woman, in Juba, said she was also gang raped by soldiers, and that women who opposed them were impaled with sticks, and six likely died.

Ethnically motivated attacks by rebels and soldiers from the Dinka and Nuer tribes have been ongoing since the outbreak of fighting in mid December, the UN said.

“Gross violations of human rights and serious violations of humanitarian law have occurred on a massive scale. Civilians were not only caught up in the violence, they were directly targeted, often along ethnic lines.”

The conflict began last Dec. 15 when South Sudanese President Salva Kiir, a Dinka, accused his Nuer vice-president, Riek Machar, of plotting a coup, a charge Machar denies. Fighting broke out among members of the presidential guard whose loyalties to the two men were split. It exploded from the capital, Juba, into the countryside, leaving at least 10,000 dead in attacks and revenge killings, and more than a million homeless. Thousands of others have been beaten, tortured, raped, robbed and kidnapped.

Canada, which has committed nearly $25 million in emergency aid to cope with the conflict, condemned the “atrocious targeted attacks against civilians,” and encouraged both sides to return to the negotiating table. Parliamentary Secretary for foreign affairs Deepak Obhrai said in a statement last month that opposition forces used radio broadcasts to target opponents, as in the Rwanda genocide.

Canada has 11 UN military observers serving in a noncombat role with the UN mission in South Sudan.

The plight of civilians who fled the fighting is dire, says Médecins Sans Frontières, which warned that “tens of thousands” sheltering in UN camps are facing “life-threatening living conditions,” including overcrowding that causes disease and malnutrition. In spite of attacks on staff and facilities, MSF has supplied basic health care through 21 projects since the conflict began.

But Raphael Gorgeu, the group’s head of mission for South Sudan, said in a phone interview, “In the last two days, with new fighting in Bentiu, we can’t land by plane or bring in additional staff and supplies.” Major routes are now blocked, and markets almost empty of food.

The Bentiu State Hospital in the country’s north was attacked earlier, and Gorgeu said that he saw “bodies of civilians strewn through the streets in grisly states of damage and decay, being eaten by dogs and birds — an affront to humanity.”

Because people were forced to flee during the planting season, Gorgeu said, the threat of malnutrition is growing. “By the end of the year, more than six million will be directly affected.”

MSF’s deputy director, Jonathan Jennings, said that Canada’s involvement in South Sudan could give it credibility to press the warring sides to cease the violence. Last year Ottawa gave about $88 million in assistance, and is providing $51 million to ward off a potential famine.

On Wednesday, ahead of Friday’s talks in Addis Ababa, Ethiopia, the South Sudanese government said it would suspend attacks on rebel forces if the rebels preserved the truce. But earlier attempted peace deals have unravelled in a tangle of chaotic motives, and there are fears that entrenched hatreds may prevail.

“There are reasonable grounds to believe that violations of international human rights and humanitarian law have been committed by both parties to the conflict,” said the UN report.